1. Field of the Invention
The present invention relates to a method for inspecting the liquid discharge condition of a liquid jet head to inspect the processed condition of the discharge ports of the liquid jet recording head mounted on a printer, a copying machine, a facsimile equipment, a word processor, or the like, from which liquid flies onto a recording medium for recording. The invention also relates to an apparatus used for inspecting the liquid discharge condition of a liquid jet recording head.
2. Related Background Art
A liquid jet recording head of a liquid jet recording apparatus comprises fine discharge ports (orifices) that discharge recording liquid, such as ink, contributing to the performance of recording (hereinafter referred to as ink, recording liquid, or some others); liquid flow paths communicated with the discharge ports; and discharge energy generating elements arranged in the corresponding liquid flow paths. Thus, the head is structured to discharge the recording liquid from the discharge ports for recording by the application of the discharge energy to the recording liquid in each of the liquid flow paths that corresponds to each of the discharge energy generating elements when the driving signals are given to each of them in accordance with the recording information, respectively. For such heads, there are known the one that discharges fine liquid droplets by the utilization of thermal energy; the one that utilizes the electro-mechanical converting elements; the one the utilizes the static-electricity; or the one that discharges the recording liquid by the utilization of the complex body formed by them in combination. Of these heads, the liquid jet recording head that discharge the recording liquid by the utilization of thermal energy makes it possible to arrange the recording liquid discharge ports in higher density, through which the recording drops are discharged to form the flying droplets. Thus, recording is possible in higher resolution, in addition to the advantage that with this method, it is easier to make the head compact. As a result, a head of the kind has been widely used in practice.
Now, in order to attain the high density of as many as approximately 600 dpi (dots per inch) as the print density, the head should be formed so that 128 liquid flow paths and discharge ports should be arrange at equal intervals in a range of approximately 5.4 mm, respectively. Then, the arrangement pitches become as fine as approximately 42 xcexcm each. Therefore, for the formation of the liquid flow path grooves and the discharge ports at such fine pitches, it is necessary to use an ultraprecision processing equipment, such as laser processing apparatus, to operate a specific machining in such a high precision.
For the laser processing apparatus to make the grooves and holes by the laser beam irradiated on the resin ceiling plate formed by the injection molding or the like, it is preferable to use the excimer laser processing. Here, as shown in FIG. 6, a laser processing apparatus of the kind comprises in general the laser oscillator 111 that outputs the laser beam L; the beam shaping optical system 112 that shapes the laser beam L irradiated from the laser oscillator 111 uniformly; the illuminating optical system 113 that irradiates the laser beam L to the mask 114; the laser mask 114 formed with the opening pattern 114a having the light transmitting regions corresponding to the processing configuration of the work piece W; and the projection optical system 115 that projects the image of the opening pattern, which is transmitted through the laser mask 114, onto the processing surface of the work piece W. Then, it is structured with a jig (not shown) to hold the ceiling plate which is the work piece W, and the movable stage 116 that moves this jig. Further, it is provided with the controlling device to control each of these members.
The ceiling plate is installed on the movable stage 116 with the jig as the work piece W to form the liquid flow path grooves and the discharge ports on it. Then, the processing surface thereof is positioned on the optical axis of the laser beam L. The laser beam L oscillated from the laser oscillator 111 is irradiated onto the processing surface of the ceiling plate through the laser mask 114 to process the liquid flow path grooves and the discharge ports.
The liquid jet recording head that uses the ceiling plate which is the work piece W, having the liquid flow path grooves and discharge ports thus formed, is structured as shown in FIG. 7. In FIG. 7, the discharge ports 102 and the liquid flow paths 103 are processed to be formed, and then, the ceiling plate 100 provided with the liquid chamber 104 is bonded with or adhesively joined to the elemental substrate (discharge energy generating means) 107 having a plurality of the discharge energy generating elements (heaters, for example) 106 arranged at given intervals in high precision by the application of ultraprecision etching techniques or the like in the state that each of the liquid flow paths 103 on the ceiling plate 100 is positioned with each of the discharge energy generating element 106, respectively. Hence, the liquid jet recording head H is manufactured.
The discharge direction of liquid discharged from the liquid jet recording head is usually controlled by the direction in which each of the discharge ports are processed and formed. However, after the laser oscillator and illuminating optical system of the laser processing apparatus are cleaned for maintenance or the like, the laser optical axis is subjected to fine deviation eventually, and the direction of the discharge ports thus processed may be varied in some cases. As a result, the discharge direction of liquid is varied, accordingly, hence causing the occurrence of such event as the creation of satellites (the smaller liquid droplets than the main liquid droplets which are discharged behind the main liquid droplets to form the images) that may invite the degradation of print quality, among some others that may take place.
Now, the inspection of the liquid discharge direction and print quality of a liquid jet recording head is usually carried out in general in such a manner that after the recording head is manufactured by bonding the ceiling plate having the discharge ports processed and formed on it with the elemental substrate (discharge energy generating means), liquid (ink) is actually discharged by driving the heaters for the intended inspection of the flying condition of liquid and the impacted point of each of them, and the like. Then, as a result of such inspection, it is determined whether or not the discharge ports thus processed and formed are suitable for the desired print quality in terms of the liquid discharge direction, the creation of satellites, or the like. The result of this determination is fed back to the manufacturing step of the ceiling plate of the recording head, thus correcting the formation angle of the discharge ports. With an inspection method of the kind, it is impossible to allow the result of the inspection, such as deviation of liquid discharge direction, to be reflected on the processing step of the ceiling plate at once so as to improve the production yield of the ceiling plate significantly.
The present invention is designed in consideration of the problems to be solved for such improvement required for the conventional techniques discussed above. It is an object of the invention to provide a method for inspecting the liquid discharge condition of a liquid jet recording head, which is capable of inspecting the discharge direction of the liquid discharged from the ceiling plate in a short period of time immediately after the discharge ports are formed on the ceiling plate, and also, capable of feeding back the correcting value at once if the liquid discharge angle is deviated from the regular value which is set in advance so as to process and form the discharge ports at the regular angle. It is also an object of the invention to provide an apparatus used for inspecting the discharge condition of a liquid jet recording head.
In order to achieve the objectives described above, the method of the present invention for inspecting the liquid discharge condition of a liquid jet recording head, which is structured by assembling a ceiling plate having discharge ports formed on it to discharge liquid and energy generating means to generate energy for discharging liquid, comprises the steps of forcing liquid to flow out from the discharge ports of the ceiling plate after the discharge ports are processed and formed on the ceiling plate, but before the assembled structure is formed; of observing and measuring the flow out condition of the liquid; and of calculating the discharge angle of the liquid.
For the method of the invention for inspecting the liquid discharge condition of a liquid jet recording head, it is preferable to make the arrangement so that the result of the calculation of the liquid discharge angle is fed back to the processing step of the discharge ports of the ceiling plate.
For the method of the invention for inspecting the liquid discharge condition of a liquid jet recording head, it is preferable to make the arrangement so that the ceiling plate is fixed in the liquid tank immediately after the discharge ports are processed and formed on the ceiling plate, and liquid is injected into the liquid tank to exert pressure on the liquid to force the liquid to flow out from the discharge ports, and that the liquid used is water or the same kind of liquid as the recording liquid actually used for recording images.
For the method of the invention for inspecting the liquid discharge condition of a liquid jet recording head, the pressure exerted on the liquid breaks the menisci of the discharge ports of the ceiling plate to form the condition of continuous flow out of the liquid. Here, it may be possible to use compressed air to exert pressure on the liquid or to adopt a vibrating plate, which is provided with piezoelectric devices, to exert pressure on the liquid.
Also, in order to achieve the objectives described above, the apparatus of the present invention for inspecting the liquid discharge condition of a liquid jet recording head comprises means for forcing liquid to flow out from the discharge ports of a single ceiling plate after the discharge ports are processed and formed thereon; and an observation and measurement system to observe and measure the flow out condition of the liquid from the discharge ports, and to calculate the discharge angle of the liquid.
For the apparatus of the invention for inspecting the liquid discharge condition of a liquid jet recording head, it is preferable to make arrangement so that the apparatus further comprises controlling means for feeding back the result of the calculation of the liquid discharge angle by the observation and measurement system to the processing step of the discharge ports.
For the apparatus of the invention for inspecting the liquid discharge condition of a liquid jet recording head, it is preferable to make arrangement so that means for forcing the liquid to flow out from the discharge ports of the ceiling plate comprises a liquid tank containing the liquid and having pressure means for exerting a specific pressure on the liquid, and a ceiling plate fixing mechanism in the liquid tank to fix the ceiling plate in it.
For the apparatus of the invention for inspecting the liquid discharge condition of a liquid jet recording head, it is preferable to arrange the liquid tank to be installed on a movable stage, and provided with an opening on the bottom thereof to enable the discharge ports of the ceiling plate to be exposed downward, and also, to enable the ceiling plate fixing mechanism to position the discharge ports of the ceiling plate on the opening and fix the ceiling plate.
For the apparatus of the invention for inspecting the liquid discharge condition of a liquid jet recording head, it is possible to structure the pressure means of the liquid tank to exert pressure on liquid in the liquid tank by supplying compressed air into the liquid tank or to provided the pressure means of the liquid tank with a vibrating plate having piezoelectric devices on the upper part of the liquid tank so as to exert pressure intermittently by driving the piezoelectric devices.
In accordance with the method of the present invention for inspecting the liquid discharge condition of a liquid jet recording head, by use of the ceiling plate immediately after the discharge ports are processed and formed, that is, the ceiling plate without discharge energy generating means assembled with it, liquid is forced to flow out from the discharge ports of the ceiling plate to observe and measure the flow out condition thereof. Then, the liquid discharge direction.and the liquid discharge angle are inspected by measuring the liquid discharge angle only with the ceiling plate having the discharge ports processed and formed, and if the result of the inspection indicates that the liquid discharge direction and angle are found to be deviated from the regular direction and value, the correcting value is promptly fed back to the processing step of the discharge ports to adjust the formation angle of the discharge ports accordingly for the improvement of the production yield thereof.
Also, in accordance with the apparatus of the present invention for inspecting the liquid discharge condition of a liquid jet recording head, it is possible to inspect the liquid discharge direction and the liquid discharge angle promptly and exactly with a simple structure provided with means for forcing liquid to flow out from the discharge ports, which is formed by a liquid tank containing the liquid and having pressure means to exert a specific pressure on the liquid, as well as formed by the ceiling plate fixing mechanism to fix the ceiling plate in the liquid tank, and an observation and measurement system to observe and measure the flow out condition of the liquid from the discharge ports to calculate the discharge angle of the liquid. Further, the apparatus is provided with controlling means to feed back the result of the calculation of the liquid discharge angle by the observation and measurement system to the processing step of the discharge ports promptly. With the structure thus arranged, the correcting value can be fed back to the processing step thereof at once for the significant improvement of the production yield of the ceiling plate that constitutes a recording head.